Zabbix polling interval for ifOutOctets affects values reported by an item

[Sarithis]

Hi,

I noticed that setting the Update interval (in sec) to a higher value like 30 or 60 causes Zabbix to report wrong values. However, if I set the update interval to 5 seconds or even 1 second, values reported by this item are correct. Here's the configuration of my item:

SNMP OID: interfaces.ifTable.ifEntry.ifOutOctets.26
Units: b/s
Use custom multiplier: 8
Update interval (in sec): 15
Store value: Delta (speed per second)

The chart of this item looks like this (values shown on this chart have NOTHING to do with the actual bandwidth on this port - they are incorrect):




When I change the update interval to 5 seconds and truncate `history_uint`, `history`, `trends` and `trends_uint` tables, the chart shows completely different values (which are correct):




Why is it behaving like that? I guess I misunderstood the way Zabbix calculates delta. Can someone shed some light on this topic?

[glebs.ivanovskis]

Most likely you are using 32 bit octet counters and it overflows several times within 30 second update interval at such bandwidth. This leads to incorrect results. Find out an OID of 64 bit counter and use that.

[Sarithis]

Most likely you are using 32 bit octet counters and it overflows several times within 30 second update interval at such bandwidth. This leads to incorrect results. Find out an OID of 64 bit counter and use that.

Thanks, it works now Looks like the 32 bit counter was indeed overflowing. I changed the OID to:

IF-MIB::if[B][COLOR="red"]HC[/COLOR][/B]OutOctets.26